So rumor from the “Ghostbusters” set is that the Prince of Darkness himself, Ozzy Osbourne, was the headliner at the heavy-metal concert scene director Paul Feig shot all last week at the Citi Wang Theatre.

Our spy on the scene overheard a couple of crew members talking about the Black Sabbath frontman outside the theater where Melissa McCarthy, Kristen Wiig, Kate McKinnon and Leslie Jones were working.

And posters outside the theater advertised a “Rock Revenge Fest featuring Ozzy Osbourne” as part of a “12 Hour Marathon of Metal.”

The Wang marquee was transformed into the Stonebrook Theatre for the shoot, with the legend “Rock Out With Your Metal Out.”

Feig, who has been tweeting a lot of teasers for the all-gal “Ghostbusters” set, hasn’t metioned Ozzy. But details about the flick have been hard to come by, so we’ll just have to wait and see if he posts a pic with Ozzy.

In the meantime, the “Ghostbusters” gals popped into the Floating Hospital for Children at Tufts Medical Center to visit patients on Saturday, dressed completely in their GB unis and carrying their proton packs.

The hospital, which is down the street from the Wang, had put up a sign in their windows saying, “Who you gonna call?” and McCarthy, Wiig, Jones and McKinnon answered.

“They were a true delight to have today,” hospital spokesgal Brooke Hynes told Channel 5. “They were so kind to all the kids and their parents. They took their time in each room visiting children as young as a few months to teens. We cannot thank them enough for the happiness and ?excitement they created.”